1. Field of the Invention
The present invention relates to an apparatus for smelting copper sulfide concentrates to extract copper.
2. Prior Art
As schematically depicted in FIGS. 1 and 2, a copper smelting apparatus comprised of a plurality of furnaces is hitherto known. The smelting apparatus comprises a smelting furnace 1 for melting and oxidizing the copper concentrates supplied together with oxygen-enriched air, to produce a mixture of matte M and slag S, a separating furnace 2 for separating the matte M from the slag S, a converter or converting furnace 3 for oxidizing the separated matte M into blister copper C and slag, and anode furnaces 4 and 4 for refining the blister copper C thus obtained to produce copper of higher purity. In each of the smelting furnace 1 and the converting furnace 3, a lance 5 composed of a double-pipe structure is inserted through the furnace roof and attached thereto for vertical movement. Copper concentrates, oxygen-enriched air, flux and so on are supplied into each furnace through the lance 5. The separating furnace 2 is an electric furnace, which is equipped with electrodes 6.
As shown in FIG. 1, the smelting furnace 1, the separating furnace 2 and the converting furnace 3 are arranged so as to have different elevations in the descending order, and are connected in series through launder 7A and 7B, so that the melt is tapped via gravitation through these launders 7A and 7B.
The blister copper C produced continuously in the converting furnace 3 is stored temporarily in a holding furnace 8, and then received in a ladle 9, which is conveyed by means of a crane 10 to the anode furnaces 4, and the blister copper C is poured thereinto through the inlet formed in the top wall.
Thus, the process up to the converting furnace 3 is carried out in a continuous manner, while the anode furnaces 4 must be operated in batches since the final composition of the copper, i.e., the quality of the copper should be controlled there. The aforesaid holding furnace 8 is provided in order to adjust the timing due to this difference in operation.
In FIG. 2, the character L denotes an example of locus of the movement of the ladle 9 which conveys the blister copper melt from the holding furnace 8 to the anode furnaces 4. In the anode furnaces 4, the impurities are oxidized and removed from the blister copper C, and copper oxide formed during the oxidation is deoxidized into copper of higher quality. Then, the resulting copper is cast into anode plates and subjected to electro-refining to obtain higher purity.
In the conventional smelting apparatus as described above, although the operations up to the converting furnace 3 are carried out continuously, the refining operations at the anode furnaces 4 are conducted in batches. Therefore, the blister copper C produced in the converting furnace 3 must be stored temporarily in the holding furnace 8. Accordingly, the installation of the holding furnace 8 is required. In addition, the ladle, the crane and so on are required in order to transport the blister copper C from the holding furnace 8 to the anode furnaces 4. Furthermore, a large amount of energy has been required to keep the temperature of the blister copper C high enough during these operations. As a result, the expenses for the installation of the facilities as well as the running costs are high, and the opportunities for the reduction in the installed area of the smelting apparatus are limited.
Moreover, when receiving the blister copper melt in the ladle or pouring the melt therefrom, the melt is caused to fall from the elevated position. Hence, there occurs great air flow, accompanied by the production of gases containing sulfur dioxide and metal fumes, caused by mechanical impact, abrupt air expansion and so on, thereby adversely affecting the environment. Therefore, fume and dust collecting installation which is effective for large areas is required.